The subject invention is directed generally to phase detectors, and more particularly to circuitry for cancelling the offset error of a phase detector.
A phase detector provides an output that is indicative of the phase between two input signals, and is commonly implemented in phase locked loops and other phase tracking circuits. A phase detector typically has an offset error wherein a phase detector output indicates zero phase while in fact the signals being compared are not in phase. Various techniques for correcting phase detector offset error have been designed, but none of such techniques are applicable to a broad range of phase detector designs, and none of such techniques maintain cancellation over variations due to integrated circuit processing, operating conditions, and aging.